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	$230.98	5.535%	$243.7647	$243.76	$243.75	$243.80
Purchase #2	$74.84	3.250%	$77.2723	$77.27	$77.25	$77.30
Purchase #3	$79.29	11.336%	$88.2783	$88.28	$88.30	$88.30
Purchase #4	$232.59	5.552%	$245.5034	$245.50	$245.50	$245.50
Purchase #5	$67.87	13.612%	$77.1085	$77.11	$77.10	$77.10
Purchase #6	$59.83	11.343%	$66.6165	$66.62	$66.60	$66.60
Purchase #7	$191.29	12.855%	$215.8803	$215.88	$215.90	$215.90
7 purchase totals =	$936.69		$1,014.4240	$1,014.42	$1,014.40	$1,014.50