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	$140.61	10.202%	$154.955	$154.96	$154.95	$155.00
Purchase #2	$155.73	5.575%	$164.4119	$164.41	$164.40	$164.40
Purchase #3	$67.27	5.874%	$71.2214	$71.22	$71.20	$71.20
Purchase #4	$199.32	13.339%	$225.9073	$225.91	$225.90	$225.90
Purchase #5	$137.67	6.164%	$146.156	$146.16	$146.15	$146.20
Purchase #6	$185.26	5.566%	$195.5716	$195.57	$195.55	$195.60
Purchase #7	$60.93	10.761%	$67.4867	$67.49	$67.50	$67.50
7 purchase totals =	$946.79		$1,025.7099	$1,025.72	$1,025.65	$1,025.80