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	$175.92	10.370%	$194.1629	$194.16	$194.15	$194.20
Purchase #2	$78.59	3.266%	$81.1567	$81.16	$81.15	$81.20
Purchase #3	$126.89	3.459%	$131.2791	$131.28	$131.30	$131.30
Purchase #4	$129.93	8.164%	$140.5375	$140.54	$140.55	$140.50
Purchase #5	$72.44	7.416%	$77.8122	$77.81	$77.80	$77.80
Purchase #6	$243.47	11.263%	$270.892	$270.89	$270.90	$270.90
Purchase #7	$122.97	3.299%	$127.0268	$127.03	$127.05	$127.00
7 purchase totals =	$950.21		$1,022.8672	$1,022.87	$1,022.90	$1,022.90