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	$53.69	10.316%	$59.2287	$59.23	$59.25	$59.20
Purchase #2	$67.55	9.198%	$73.7632	$73.76	$73.75	$73.80
Purchase #3	$136.63	12.198%	$153.2961	$153.30	$153.30	$153.30
Purchase #4	$196.81	9.270%	$215.0543	$215.05	$215.05	$215.10
Purchase #5	$218.38	4.533%	$228.2792	$228.28	$228.30	$228.30
Purchase #6	$113.59	11.273%	$126.395	$126.40	$126.40	$126.40
Purchase #7	$186.88	5.125%	$196.4576	$196.46	$196.45	$196.50
7 purchase totals =	$973.53		$1,052.4741	$1,052.48	$1,052.50	$1,052.60