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	$135.39	12.376%	$152.1459	$152.15	$152.15	$152.10
Purchase #2	$109.65	11.390%	$122.1391	$122.14	$122.15	$122.10
Purchase #3	$100.84	5.165%	$106.0484	$106.05	$106.05	$106.00
Purchase #4	$167.80	3.785%	$174.1512	$174.15	$174.15	$174.20
Purchase #5	$54.88	12.743%	$61.8734	$61.87	$61.85	$61.90
Purchase #6	$209.33	13.864%	$238.3515	$238.35	$238.35	$238.40
Purchase #7	$216.83	9.800%	$238.0793	$238.08	$238.10	$238.10
7 purchase totals =	$994.72		$1,092.7888	$1,092.79	$1,092.80	$1,092.80