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	$41.81	4.302%	$43.6087	$43.61	$43.60	$43.60
Purchase #2	$246.98	10.851%	$273.7798	$273.78	$273.80	$273.80
Purchase #3	$172.96	7.142%	$185.3128	$185.31	$185.30	$185.30
Purchase #4	$167.95	8.309%	$181.905	$181.91	$181.90	$181.90
Purchase #5	$93.69	12.425%	$105.331	$105.33	$105.35	$105.30
Purchase #6	$41.48	9.307%	$45.3405	$45.34	$45.35	$45.30
Purchase #7	$204.82	9.724%	$224.7367	$224.74	$224.75	$224.70
7 purchase totals =	$969.69		$1,060.0145	$1,060.02	$1,060.05	$1,059.90