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	$39.90	10.173%	$43.959	$43.96	$43.95	$44.00
Purchase #2	$184.65	3.513%	$191.1368	$191.14	$191.15	$191.10
Purchase #3	$166.32	11.730%	$185.8293	$185.83	$185.85	$185.80
Purchase #4	$109.75	10.258%	$121.0082	$121.01	$121.00	$121.00
Purchase #5	$48.65	3.363%	$50.2861	$50.29	$50.30	$50.30
Purchase #6	$181.32	8.276%	$196.326	$196.33	$196.35	$196.30
Purchase #7	$232.71	11.111%	$258.5664	$258.57	$258.55	$258.60
7 purchase totals =	$963.30		$1,047.1118	$1,047.13	$1,047.15	$1,047.10