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	$237.37	3.276%	$245.1462	$245.15	$245.15	$245.10
Purchase #2	$12.36	10.104%	$13.6089	$13.61	$13.60	$13.60
Purchase #3	$12.70	5.582%	$13.4089	$13.41	$13.40	$13.40
Purchase #4	$187.56	4.661%	$196.3022	$196.30	$196.30	$196.30
Purchase #5	$147.30	4.708%	$154.2349	$154.23	$154.25	$154.20
Purchase #6	$228.51	6.456%	$243.2626	$243.26	$243.25	$243.30
Purchase #7	$156.66	5.516%	$165.3014	$165.30	$165.30	$165.30
7 purchase totals =	$982.46		$1,031.2651	$1,031.26	$1,031.25	$1,031.20