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	$190.98	4.731%	$200.0153	$200.02	$200.00	$200.00
Purchase #2	$181.30	4.654%	$189.7377	$189.74	$189.75	$189.70
Purchase #3	$44.82	4.203%	$46.7038	$46.70	$46.70	$46.70
Purchase #4	$178.33	4.671%	$186.6598	$186.66	$186.65	$186.70
Purchase #5	$200.90	4.185%	$209.3077	$209.31	$209.30	$209.30
Purchase #6	$164.52	12.871%	$185.6954	$185.70	$185.70	$185.70
Purchase #7	$55.69	6.322%	$59.2107	$59.21	$59.20	$59.20
7 purchase totals =	$1,016.54		$1,077.3304	$1,077.34	$1,077.30	$1,077.30