Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$181.31	7.803%	$195.4576	$195.46	$195.45	$195.50
Purchase #2	$221.77	10.579%	$245.231	$245.23	$245.25	$245.20
Purchase #3	$39.38	13.332%	$44.6301	$44.63	$44.65	$44.60
Purchase #4	$235.30	12.470%	$264.6419	$264.64	$264.65	$264.60
Purchase #5	$187.71	13.241%	$212.5647	$212.56	$212.55	$212.60
Purchase #6	$136.85	3.835%	$142.0982	$142.10	$142.10	$142.10
Purchase #7	$175.33	12.224%	$196.7623	$196.76	$196.75	$196.80
7 purchase totals =	$1,177.65		$1,301.3858	$1,301.38	$1,301.40	$1,301.40