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	$137.61	9.461%	$150.6293	$150.63	$150.65	$150.60
Purchase #2	$70.38	9.631%	$77.1583	$77.16	$77.15	$77.20
Purchase #3	$211.66	13.630%	$240.5093	$240.51	$240.50	$240.50
Purchase #4	$156.96	9.303%	$171.562	$171.56	$171.55	$171.60
Purchase #5	$240.51	6.243%	$255.525	$255.53	$255.55	$255.50
Purchase #6	$26.55	8.798%	$28.8859	$28.89	$28.90	$28.90
Purchase #7	$191.28	8.872%	$208.2504	$208.25	$208.25	$208.30
7 purchase totals =	$1,034.95		$1,132.5202	$1,132.53	$1,132.55	$1,132.60