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	$200.85	10.294%	$221.5255	$221.53	$221.55	$221.50
Purchase #2	$48.30	13.130%	$54.6418	$54.64	$54.65	$54.60
Purchase #3	$65.91	6.279%	$70.0485	$70.05	$70.05	$70.00
Purchase #4	$91.73	4.820%	$96.1514	$96.15	$96.15	$96.20
Purchase #5	$210.41	6.134%	$223.3165	$223.32	$223.30	$223.30
Purchase #6	$199.98	11.165%	$222.3078	$222.31	$222.30	$222.30
Purchase #7	$156.97	9.847%	$172.4268	$172.43	$172.45	$172.40
7 purchase totals =	$974.15		$1,060.4183	$1,060.43	$1,060.45	$1,060.30