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	$188.81	6.528%	$201.1355	$201.14	$201.15	$201.10
Purchase #2	$166.94	5.440%	$176.0215	$176.02	$176.00	$176.00
Purchase #3	$40.81	4.814%	$42.7746	$42.77	$42.75	$42.80
Purchase #4	$106.28	4.846%	$111.4303	$111.43	$111.45	$111.40
Purchase #5	$144.75	12.188%	$162.3921	$162.39	$162.40	$162.40
Purchase #6	$81.46	5.347%	$85.8157	$85.82	$85.80	$85.80
Purchase #7	$245.46	12.107%	$275.1778	$275.18	$275.20	$275.20
7 purchase totals =	$974.51		$1,054.7475	$1,054.75	$1,054.75	$1,054.70