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	$89.94	5.607%	$94.9829	$94.98	$95.00	$95.00
Purchase #2	$220.91	13.211%	$250.0944	$250.09	$250.10	$250.10
Purchase #3	$42.78	6.830%	$45.7019	$45.70	$45.70	$45.70
Purchase #4	$210.79	9.736%	$231.3125	$231.31	$231.30	$231.30
Purchase #5	$179.43	3.824%	$186.2914	$186.29	$186.30	$186.30
Purchase #6	$72.63	7.399%	$78.0039	$78.00	$78.00	$78.00
Purchase #7	$148.42	13.140%	$167.9224	$167.92	$167.90	$167.90
7 purchase totals =	$964.90		$1,054.3094	$1,054.29	$1,054.30	$1,054.30