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	$103.59	7.515%	$111.3748	$111.37	$111.35	$111.40
Purchase #2	$55.78	9.340%	$60.9899	$60.99	$61.00	$61.00
Purchase #3	$218.49	7.870%	$235.6852	$235.69	$235.70	$235.70
Purchase #4	$41.39	4.617%	$43.301	$43.30	$43.30	$43.30
Purchase #5	$124.81	12.183%	$140.0156	$140.02	$140.00	$140.00
Purchase #6	$228.72	6.272%	$243.0653	$243.07	$243.05	$243.10
Purchase #7	$102.73	8.279%	$111.235	$111.24	$111.25	$111.20
7 purchase totals =	$875.51		$945.6668	$945.68	$945.65	$945.70